Fluid seal



arch 25, 1947i.` J F JOY FLUID SEAL FilQd plvl 2l, 194:5

y bvucmon Jamel-1h F. July Patented Mar. 25, 1947 FLUID SEAL Joseph F.Joy. Washington, D. C.

Application April 21, 1943, Serial No. 483,841

5Claims.

(.Granted underl the act of March 3, `1883,.

amended April 30, 1928; 370 0. G. 757) v l The invention describedherein may be manufactured and used by or for the Government forgovernmental purposes, without the payment to me of any royalty thereon,y

The present invention relates generally to the art of packing or sealingof reciprocal or rotatl of the hydro-pneumatic type, liquid and gaspressures are arranged in such association as to absorb the shock offiring and return the gun to battery. The hydraulic liquid is usually alow pour point oil, and nitrogen gas is most frequently used asthepneumatic element. 'I'he proper functioning of such mechanisms dependsupon an extremely exact separation between the hydraulic and pneumaticmediums.

InA operation the gun upon being red moves into recoil position. It isresisted in such movement by a recoil piston attached by means of apiston rod to the gun, usually at the breech ring.

'The recoil movement forces the oil or other hydraulic medium from therecoil cylinder, usually through throttling ports or orifices into arecuperator or accumulator cylinder filled with gas forming the`pneumatic medium of the system. 'Ille recoil forces Aare finally in thisway overcome as a-result of the throttling orifices and the increasingpressure of the gas element, after which the gun is returned to batteryor ring position through the expansion of the pressure built up in thepneumatic element within the recuperator cylinder during the period ofrecoil.

Aeration of the hydraulic medium as a result of its absorption of gasfrom the pneumatic medium seriously impairs ormay even destroy theproper functioning of the mechanism chiefly because of the difference inthe rate of throttling between aerated and non-aerated liquids. In orderto avoid aeration of the oil or hydraulic medium as would result fromits direct contact with the gas or pneumatic medium, the gas and liquidare deiinitely separated from contact with each other, usually by meansof a oating piston arranged in the recuperator cylinder.

With respect to artillery pieces, they are usually constructed with apreponderance of Weight atthemuzzle end of the piece. Balancing devicescommonly called equilibrators are employed to counteract thispreponderance of weightl for the purpose of reducing the forcey requiredfor elevating the gun. f In both recoil mechanisms and equilibrators,the matter of frictional resistance of the packing mediums is ofparamount importance. In the case of recoil mechanisms, such frictionalresistance to movement increases the forces acting upon the gunstrunnlons and supporting .carriaga In the case of equilibrators, anysuch frictional resistance increases the force required for movement ofthe gun, and this, being usually done by hand, makes it imperativeespecially in the case of large guns that equilibrator packing frictionsbe held to an absolute mini,- mum. Therefore, the many common types. ofhydraulic and pneumatic packings ordinarily used for other purposes arein general notsatisfactory for the packing of the pistons and rods ofrecoil and equilibrator mechanisms. This is due chiefly to the highfriction of such packings and their being susceptible to gas diffusionthrough their various compositions.

To overcome this, it has been the practice of artillery engineers topack such mechanisms with combination packings, a typical form of which,

the Well-known French type, comprises separate rings of rubber andleather backed up by pressure loaded anged silver rings. Sealing isattained by means of the leather and rubber rings and the silver ringsare provided for the purpose of obturation. Obviously such refinedconstruction requires close and accurate machining of cylinders and rodsand their ultimate honing to accurate lits, one with the other. These tsin practice are so close as to preclude the possibility ofAinterchangeability of parts, thus making it necessary when repairs oradjustments are required that the mechanism be returned to themanufacturer or arsenal for such operations.

It should also be noted that the use of hydraulic mechanisms is atpresent under consideration by ordnance engineers for the purpose of gunpointing. Such mechanisms usually consist of a hydraulic pressuregenerator combined with a suitable iluid motor for the actuation oftraversing n and elevating gears employed in positioning the gun withrelation to the target.

'These mechanisms are sometimes referred to as 55 oil gears and includeenclosures containing fluid at relatively high working pressures fromwhich input and output shafts protrude. Itis common knowledge that it isextremely difficult to avoid l hydraulic mechanism capable of operatingat It is therefore anobject of this invention to provide a standard formof piston and rod packing of low frictional characteristics,particularly result from-the use of -various newly-developedstanceswould result in increased pressure and 'friction at the seal. This is infact a common occurrence in such packings and is known 'to recoil oils.It is accordingly an important feature of my invention to eliminate thisdefect by providinga packing which allows ample room adaptable for usein gun recoii and equilibrator Y mechanisms and capable ofintcrchangeability and replacement in the eld.

Another object of the invention is to provide a packing or sealingdevice of the character herein described wherein a rigid supporting ringis provided and to which one or more flexible sealing rings are secured.

A further object of the invention is to provide a sealing device whereina rigid supporting ring has an axially extending integral flangethereon, whereby flexible sealing rings can be secured thereto, one oneach side of said flange.

A still further object of the invention is to provide, in a sealingdevice, exible sealing lips which are formed of a compound which has notonly wear resisting qualities but also qualities which will not permitoil and other fluids to pass therethrough.

A still further object of the invention is to provide a sealing devicehaving a rigid supporting ring and flexible sealing members securedthereto, wherein the flexible members are formed of a compositionconsisting mainly of a synthetib rubber and a finely powderedanti-friction metal.

A still further object of this invention is to provide an eifective anddependable seal for the rotary members of fluid mechanisms particularlywhere it is desirable to prevent leakage or loss of iluidundervconditions o both highpressure and high rotational operatingspeeds.

Still another object is to provide an easily infor expansion without anyappreciable increase in pressure or friction.

Other and more specic objects of the .invention will appear more fullyupon a reading of the following description taken in connection with theaccompanying drawing wherein:

Fig. v1 is a vertical section through a conventional cylinder, pistonand rod showing the seali ing device of my invention assembled in properrelation to the other parts;

Fig. 2 is an enlarged vertical section through a sealing device forminga preferred embodiment of my invention;

Fig. 3 is a plan view of the device shown in Fig. 2;

Fig. 4 isa plan view of the back or opposite face of the ring from thatshown in Fig. 3;

stalled rotary shaft seal capable of withstanding severe operatingconditions and composed of a material which embodies a high degree ofheat conductivity whereby the heat resulting fromV operation iseffectively conducted away and dissipated into the supporting frame.

One of the difculties attendant upon the use of various syntheticcompounds such as neoprene for packing purposes has been the tendency ofsuch materials to absorb or react with certainoils used in `conjunctiontherewith. This absorption or reaction results in an expansion ofthematerial which in certain cases may in tum cause an increase in pressureand consequently friction at the seal. For example,

referring briefly to Fig. 1 it will be noted that my improved packing isshown'at 8 and again at 6 as being wholly contained' within chambers ofrelatively fixed volume in the piston and gland. respectively. It willbe further noted that the synthetic material in each case occupies onlya portion of the total available volume of these chambers so that amplefree volume remains to accommodate any expansionl of the packingmaterial. In conventional packings on the contrary where high pressuresare involved, this space would ordinarily be entirely lled with thesynthetic material under lan initial pressure. It is obvious that anyabsorption of oil and resultant expansion of the packing under suchcircum- Fig. 5 is a fragmentary section of a duid enclosure showing arotating shaft extending from the interior to the exteriorof saidenclosure and the manner in which a sealing ring forming a preferredlembodiment of my invention may be Y used to prevent loss of fluidthrough the opening provided for the rotation of said shaft; and

Fig. 6 illustrates an enlarged fragmentary Vcross sectional view takenthrough one of the ilexible sealing members or annular rings illustratedin Fig. 2.

Referring now more particularly to the drawing, for purposes ofconvenience Fig. 1 shows a plurality of the sealing devices embodying myinvention as they are applied to a conventional cylinder and piston.While it has been explained hereinbefore that the invention isIprimarily intended for use withartillery equipment, it will be clearthat it will also have many other uses common to hydraulic and pneumaticdevices. In Fig. l, a conventional cylinder is shown at I having apiston 2 therein to which is secured a piston c rod 3. One end of thecylinder is shown as being provided with a cap 4 having an annular ange5 thereon in spaced relation to the piston rod 3 so as to provide anannular retaining cavity 6'. A cap l is then shown as located around thepiston rod to maintain the sealing device in place in the retainingcavity 6.

Two of these devices are shown as surrounding the piston rod 3 and areused to prevent fluid from passing outwardly along the piston rod. Thepiston 2 is also provided with an annular groove 8', which forms aretaining cavity with the inner wall of the cylinder I. A plurality ofmy sealing devices are shown inserted within 'this cavity 8'. Two areshown at the left hand side of the cavity for the Apurpose of preventingthe ilow of fluid toward the right and two other devices are placed atthenright hand end of the cavity to prevent the flo'w of fluid towardthe left. This is merely illustrative of the manner in which the sealingdevices of my invention may be used. However, as explained above, theymay also be used in recoil mechanisms and equilibrators wherein it isdesired to prevent oil or other iluid on one side of a piston frombecoming aerated by gas on the opposed side of the piston.

Referring now more specically to Fig. 2,' the I exible ring members. Theinner ringfbeing inl dicated by the numeral II is secured to thesupporting ring at its walls I2 and I3, the wah I2 being secured to thecylindrical section and the wall I3 being secured directlyto the base ofthe ring. The inner Wall I4 of the exible ring extends in a generallyaxial direction but is flared inwardly slightly and terminates in asealing lip i5 whichin turn is spaced from the cylindrical section I bymeans of an annular groove I8.

The outer sealing ring I 'I is similar to that just described and issecured to the supporting ring at its walls I8 and I3, the inner wall I8being secured to the cylindrical section I0 and the wall I9 beingsecured directly to the base of the supporting ring. The outer sealingwall or periphery 20 of the flexible ring I'I also extends in agenerally axial direction and is flared outwardly slightly andterminates in a flexible sealing-lip 2|, which is also spaced from thecylindrical section I0 by means of an annular groove v22.

A plurality of communicating passages are prothis ring is inserted in aretaining cavity, the inner and outer flexible walls I4 and 20 thereofwill be flexed inwardly toward each other until they becomesubstantially parallel, thus forming a tight seal against the walls ofthe cavity. If iluid under pressure attempts to move past the seal aquantity of it willnrst become lodged within either or both of theannular grooves I6 and 22 and thus exert further pressure outwardlyagainst.

the walls of the cavity. It ,will thus be evident that the more pressureexerted the tighter will lthe flexible sealingflips be pressed againstthe walls of the cavity and thus form a better seal. It should also benoted that'the cylindrical section I0 of the supporting ring extends inan axial direction beyond the sealing lips I and 2I so that when two ormore of these rings are placed in a cavity adjacent each other as shownin Fig. 1, the sealing lips will still remain free to be flexed andperform their objectives'.

Referring now to Fig. 5 of the drawings, I have shown an operating shaft30 extending from the interior of a fluid pressure mechanism which maybe either a pump or a motor, and which has an area generally designatedby the numeral 3I which is subject to relatively high operatingpressures. which serves to confine the fluid under pressure within thespace 3|. The shaft 30 extends through an aperture 33 in the wall 32 andis mounted for rotation therein. 'I'he wall 32 is also formed with anannular flange member 34 which surrounds the shaft 30 and provides anannular space 3-5 therearound. This annular space A portion of the Wall32 is illustratedfv pressure from the space 3| to flow around the shaft3c and act against the operating faces and lips of the sealing member.In this case the seal operates both to prevent the escape of fluid fromspace y3| and to absorb and transmit the frictional heat induced by therotation of shaft away from the sealingarea.

While it will be clear that my inventionresides in the novel features ofdesign, the invention itself goes further and is considered as alsoresiding in the composition of not only theflexible ring members, butalso the rigid supporting ring as well.

As far as the supporting ring is concerned a number of substances may'be satisfactorily used, such as bronze, steel with a thin layer ofsilver on the outer walls, various plastics, or molded hard rubber.Almost any material having antifriction characteristics can be usedalthough experiments have disclosed that certain materials are bettersuited for this purpose than others. By process of elimination, it hasbeen determined 'that molded` hard rubber is lwell suited for the 35contains one of my sealing units 9 heldin place .ange 34 and it shouldbe noted that the aperture l33 is of suflicient size to freely allowfluid -under y'compound' with an anti-friction material.

purpose'.

With respect to the flexible rings which are secured to the rigidsupporting ring, numerous `materials have been compounded and have'beenthe numerous synthetic rubbers and plastics available and after aconsiderable amount of experimentation vit was discovered that neoprenecompounds possessed the most desirable characteristics.

It was necessary in order to obtain the desired low friction values toimpregnate the "neoprene Such materials of course are many and varied.`However, for best results it should be a material which would bond Wellwith the neoprene; that is, would serve not only to lower the frictionof the resulting material but also be capable of acting as a filler inplace of the usual carbon black. There are numerous metals which satisfythese requirements such as bronze, brass, silver, and the like. However,experimentation has shown that finely powdered bronze is verysatisfactory and not only reduces the friction value but also bonds wellwith and acts as a -i'lller for the neoprene compound.

To begin with a compound substantially as fol- 1ows was used:

O11 (Circo light) 2 Neozone .6 Zuic Oxido 1 5 Oumar R. S 2. 6 BronzePowder 45 It appeared, however. that this compound was.

too soft for the purposes of thisinvention and in order to obtain agreater hardness, the same compound was used except that 'l1/2 parts ofchannel black were added to the -compound as a hardeningv agent. Thiscompound'then showed some improvement in hardness but it was desired to`llower the friction value' still further. Another compound was thenmade consisting of the following materials:

Materials @ggg Neoprene "GN" A I 54 Magnesium Oxido (extra light) 2Carbon Binck (P33) 30 Stcnrc Acid 3 Oil (Circo light). 2 Neozonc D.-...6 Zinc Oxide.. 1.15 Oumar 2.6 Bronco Powder 80 f 173.0

It will be noted that this is substantially the same as the firstcompound used except that the bronze powder content was almost doubled.It was determinedv that this compound had the desired characteristicsnot-only as to hardness but also as to its anti-friction qualities.

Other subsequent compounds were also made wherein shredded leather wasused, and Pliolite,

which is a commercial name for a rubber stiil'- ener. The .shreddedleather compound indicated the sealing lips to be noticeably brittle andhence were likely to crack-as a result of handling and operatingconditions.

The compound using Pliolite appeared to be rm yet was somewhat tacky andnot too resilient.

Subsequent tests of the various compounds mentioned under conditions ofhigh fluid pressures and high operating speeds showed conclusively thatall compounds containing metallic dust particularly bronze powderoperated at greatlyv reduced temperatures as compared to non-metalliccompounds. It was further found that the reduced operating temperatureof the metalizred compounds was due to their possessing suiiiciem-l heatconductivity to carry the heat away from the rubbing surfaces anddissipate the same into the supporting frame, whereas, the

non-metallic compounds allowed the heat to concentrate at therubbing'surfaces thus causing early destruction of the seal underconditions oi.' high operating speeds. The latter is particularly trueof high speed shaft seals and more so where the latter operate underhigh uid pressure.

Numerous other tests were made involving various compounds but it wasdetermined that the one containing the 80 parts of bronze powder byweight appeared to be the best. Extensive tests have been carried outwith this compound and it has proven most satisfactory. While I haveexplained above in detail some of the compounds used and tested and Ihave indicated the one which hasA appeared lthus far to be mostdesirable, I do not wish to be limited to any one particular compound asfar as this invention is concerned. It is contemplated that others maybe used without departing in any way from the spirit of the invention,provided, of course, that they possess the necessary characteristics asoutlined hereinbefore. Any desired means can be used for securingpermanently the flexible rings to the rigid supporting base,such as byusing a cement for bonding, or curing under high pressures andtemperatures, and the like. H

One method which has proven satisfactory is to first mold the rubbersupporting base and cure it for half vof its required time and then moldthe resilient rings thereto and cure the entire ring 8 for the remainingtime.` This has proven satisfactory where the curing time of theresilient rings is approximately half that of the supportingring.

Another method oi securing which has proven satisfactory is to make aliquid by dissolvinga portion of the flexible ring compound in benzine,coating the rigid supporting ring with this liquid, and immediatelyapplying the flexible rings thereto and then curing in the usual manner.'I'.he specific securing means is not important,

however, as long as a permanent bond is proi vided between the twoflexible rings and the rigid supporting ring.

Itis to be particularlyJ noted that each oi' my improved iiuid seals isa complete self-contained sealing unit within itself. They do notrequire adjustment for wear and in fact the very purpose of thecylindrical section Ill extending beyond the tips of the sealing lips I5and 2| is to prevent any pressure other than that of the uid acting uponthe sealing sections. Each seal as a unit is capable of being securelyheld in operating position without the holding force in any way actingupon or interfering with the freedom of action of the sealing lips.

The importance of using iinely pulverized metallic dust as a.constituent of the compound used for forming the flexible sealingsections of the seals cannot be overemphaszed. I have found that finemetal dust, particularly bronze powder, compounds well with vmostsynthetics such as "neoprene without'materially aiecting the resiliencyand elasticity of the product. I have also found that the finelypowdered metal dust greatly contributes to the heat conductivity of thecompound which is an element of great importance where seals are for useunder conditions oi high operating speeds and pressures as isparticularly true in the case of rotary seals. Where it is desirable todissipate the heat from rubbing surfaces of rotary type seals into thesupporting frame this can be best achieved through the use of metal Tring sections and sealing lip facings formed of a high percentage ofbronze powder or other heat conducting anti-friction metallic powder.

From the foregoing it .will be obvious that I have provided a packing orsealing ring which not only possesses a novel design but is also com-DOunded in a novel manner. The invention herein resides as pointed outabove not only in the form of the ring itself, but also in the compoundswhich make up the various components of the ring. In actual tests it hasbeen proven that the frictional value is extremely low and yet thesealing qualities are very high. Little or no socalled "trading asbetween oil and gas positioned at opposite sides of the piston withinthe cylinder of gun recoil mechanisms is obtained.

It is contemplated that the invention may assume other forms than thatdisclosed herein,l

change being made as regards the particular device described, provided,however, that such changes come within the scope of the appended claims.

I claim:

l. A sealing device for spaced-apart generally parallel co-extensivewalls, comprising: rigid means, having a first leg portion adapted forposition transversely with respect to said co-extensive walls, and atleast one second leg portion extending laterally from said iirst legportion intermediate its transverse margins, said first and second legportions being adapted to form at 9 least two grooves co-extensive withsaid walls; resilient sealing means, disposed in each of said grooves,each having a recess formed therein, providing a base portion abuttingthe adjoining surface of said first leg and a pair Vof sealing lips eachof tapered construction and extending from said base portion, eachsealing means, when the sealing device is assembled with saidco-extensive walls, having spaced surfaces, one of which is adapted toengage and lie along the adjoining one of said co-extensive walls, andthe other of which abuts and lies along the adjoining surface of saidsecond leg portion, and 'each sealing means also having facing surfacesextending from said base portion in diverging relation to intersectionwith said spaced surfaces, thereby forming the tapered sealing lips; theforegoing construction being such that fluid pressure on said sealingdevice urges said base portion against the adjacent surface of said rstleg and each of said sealing lips against its respective wall and havingan annular recess generally co-axial with` said grooves, forming a baseportion bearing against the adjoining surface of the base of the T, anda pair of sealing lips, each tapered in cross-section and extending fromsaid base portion, each sealing means, when the sealing device isassembled with said concentric spaced-apart surfaces, having generallyconcentric inner and outer walls respectively bearing against theadjoining surface of the stem of the T and'against an adjoining one ofsaid concentric spaced-apart walls, and each sealing meansalso havingfacing walls extending from said base portion in diverging relation tointersection with said inner and outer walls, thereby forming thetapered sealing lips; the foregoing construction being such that uidpressure exerts force on each of saidsealing means, holding said sealingmeans in position in its groove, and also urging said sealing lipsagainst the adjoining wall surface and against the adjoining surface ofthe stem of the T.4 l

3. A sealing device for concentric spaced-apart surfaces, comprising: anannular rigid supporting means of substantially T cross-section, thebase of the T being .adapted for position in transverse relation withrespect to said spaced-apart surfaces, forming concentric inner andouter annular grooves directed toward respective ones of saidspaced-apart surfaces; and resilient sealing means disposed in each ofsaid grooves, each having an annular recess generally co-axial with saidgrooves, forming a base portion bearing against the adjoining surface ofthe base of the T, and a pair of identical sealing lips, each tapered incross-section and extending from Ysaid base portion, each sealing means,when the sealing device is assembled with said concentric spaced-apartsurfaces, having generally concentric inner and outer walls respectivelybearing against the adjoining surface of the stem ofthe T and against anadjoining one of said concentric spaced-apart walls, and each sealingmeans also having facing walls extending from said base portion indiverg- 10 ing relation to intersection with said inner and outer-walls,thereby forming the tapered sealing lips; the'foregoing constructionbeing such that uid pressure exerts force on each of said seal, ingmean'sfholding said sealing means in position in its groove, and alsourging said sealing lips against the adjoining Wall surface and againstthe adjoining surface of the stem of the T with equal force.

4. A sealing device for concentric spaced-apart surfaces, comprising: anannular hard rubber supporting means of substantially T cross-section,

' tapered in cross-section and extending from said base portion, eachsealing means, when the sealing device is assembled with said concentricspaced-apart surfaces, having generally concentric inner and outer-wallsrespectively bearing against the adjoining surface of the stem of the Tand against an adjoining one of said concentric spaced-apart walls, andeach sealing means also having facing walls extending from said baseportion in diverging relation .to intersection with said inner and outerwall, thereby forming the tapered sealing lips; the foregoingconstruction being such that fluid pressure exerts force on each of saidsealing means, holding said sealing means in position in its groove, andalso urging said sealing lips against the adjoining wall surface andagainst the adjoining surface of the stem of the T; each of saidresilient rubber sealing means being bonded to said hard rubbersupporting means along the contacting surfaces of the base of said T andthe base portion of said sealing means, and also along the contactingsurfaces of the stem of the T and an adjacent one of the sealing lips.

5. A sealing device for apparatus including concentric spaced-apartsurfaces, comprising: an annular rigid supporting means of substantiallyT cross-section, the base of the T being adapted for position intransverse relation with respect to said spaced-apart surfaces, formingconcentric inner and outer annular grooves adapted to be directed towardrespective ones of said spacedapart surfaces; and resilient sealingmeans disposed in each of said grooves, each having an annular recessgenerally coaxial with said grooves, forming a base portion bearingagainst the adjoining surface of the base of the T, and pair ofidentical sealing lips, each tapered in cross-section and extending fromsaid base portion, each sealing means, when the sealing device isassembled with said concentric spaced-apart surfaces,

having generally concentric inner and outer walls respectively bearingagainst an adjoining one of said concentric spaced-apart walls andagainstthe adjoining surface of the stem of the T, and each sealingmeans also having facing walls extendingfrom said base portion indiverging relation to intersection with said inner and outerl walls,thereby forming the tapered sealing lips; the foregoing constructionbeing such that uid pressure exerts force on each of said sealing means,holding said sealing means in position in A 11,Y its grooves, andalsourging said sealing lips against the adjoining wall sin'laee and againstthe adjoining surface oi.' the stem oi' the T with equal force; theextremity of the stem being disposed in a piane positioned Vbeyond aplane including thefreetipsofsaidseaiinglipssoas to be in positiontobear against part of said apparatus or a portion of another sealingdevice and thereby relieve said sealing lips of all force other thanthat caused by uid pressure, and the peripheral margin of said stembeing formed with spaced-apart notchesto provide for fluid communicationbetween said sealing means.

1' JOSEPH F. JOY.

BUES CITED 4 UNITED STATES PATENTS Number Name Date 2,046,724 BufiingtonJuly 7, 1935 2,067,499 Milimine Jan. 12. 1937 2,211,899 Kriegbaum Aug.20, 1940 2,214,261 Roth Sept. 10, 1940 2,263,178 -Lignian et al. Nov.18, 1941 2,007,501 Mlimine July 9, 1935 2,081,040 King May 18, 19372,244,135 Wallace June 3, 1941 1,555,023 Prokoilef! Sept. 29, 19252,238,654 Maier Apr. 15, 1941 2,365,774 Pool Dec. 26, 1944 OTHERREFERENCES Report No. 421, Neoprene Type FR, D. F. Fraser, May.1942, E.I. du Pont de Nemours az Co., Wilmington, Delaware.

